The invention relates to optical semiconductor transmitters or semiconductor amplifiers having a periodic structure.
The transmission of communications via optical fibers permits very high data rates. Due to the dispersion behavior of optical fibers, the transmission of communications over long distances requires lasers which emit a single longitudinal mode. EP-A 0,149,462 discloses that it is possible, by integrating a diffraction grating in a semiconductor laser so as to reduce the number of modes emitted by the laser. Such lasers are called DFB (distributed feedback) lasers. It can be demonstrated that even a DFB laser emits in two longitudinal modes which is not the optimum with a view toward the conversion of electrical energy to radiation energy.
Moreover, EP-A 0,213,965 discloses the connection of an semiconductor laser with a tunable resonator to thus realize a reduction in the number of longitudinal modes. The resonator disclosed in this publication also includes a diffraction grating so that, with this solution as well, two longitudinal modes are emitted in principle.